The present invention relates to the field of diagnostic techniques and medical tests by means of microplates, and more particularly the automatic treatment of such plates, and has for its object a washing and extraction head for a washing robot, as well as an apparatus or a microplate washing station comprising such a head.
At present, numerous medical tests have been carried out in batteries by means of microplates in the form of a support plate of plastic material provided with a plurality of reinforcements in the form of wells each receiving a sample to be analyzed, said analysis wells being generally arranged in a flat matrix arrangement of rows and columns that are mutually perpendicular.
Before analysis, these microplates must be treated for the preparation and handling of the different samples in a form (in solution) suitable for the tests and/or for the operative manipulations to be carried out and, after removal or analysis, it is necessary to clean said wells by washing, possibly several times, and rinsing.
For this purpose, said microplates are placed in or brought into a washing robot or a washer principally constituted by a support adapted to receive said microplates and by a removable washing and extraction head associated with fluid supply and removal circuits.
The support of the microplates and the head can be moved relative to each other in at least one straight direction disposed in the plane of the microplate in the treatment position and in a direction perpendicular to said plane.
Such a head is, in known manner, movable above the microplate or plates in the treatment position and generally comprises a row of needles or distribution tubes connected to a liquid supply circuit for washing and/or rinsing and a row of needles or suction tubes connected to an evacuation and/or recovery circuit, with each needle of the first type being associated a needle of the second type with an offset in the direction of movement of relative translation between said head and said microplates in the course of treatment of these latter, a number of pairs of needles of the two types being equal to the number of wells per column or per row, or to a fraction of this number, and a spacing between two adjacent pairs of needles being equal to the spacing between two adjacent wells of the same column or row, or to a multiple of this spacing.
Automatic microplate washing apparatus or stations provided with such a head, are also known and there can, for example, on this subject, be cited the automatic washer known under the name LAVEUR LP40 of the company ADIL INSTRUMENTS.
These known washers and heads are well adapted for the treatment of microplates whose wells receive the usual samples in liquid or dissolvable solid form.
However, for neonatal diagnosis, there exists a technique of removal of particular samples on blotting paper. The sample is deposited on the blotting paper by direct removal from the heel of the newborn. This method facilitates the sending of samples to a central analysis laboratory (sent in an envelope, not a specimen tube).
This type of test is very widespread in Europe. For analysis, the laboratory recovers the blood specimen to be analyzed by cutting out one or several discs of standard dimension from the sheet of blotting paper impregnated with blood (3.2 mm or 4.5 mm diameter). The sample discs to be analyzed are then deposited in the wells of a microplate. The addition of a buffer (dilution solution) permits dissolving the specimen to be analyzed. After prolonged incubation, the paper disc must be withdrawn from the microplate to be able to continue the qualitative analysis. The plate thus follows a conventional cycle of washing and then reading at the end of diagnosis.
At present, in the automatic processes for treating microplates, there must be two different devices for carrying out the phases of extraction of the discs and washing of the microplate, so as to avoid plugging the suction circuit for the liquid of the washing apparatus.
Thus, the extraction of the discs is carried out by or on an extractor for sucking up the discs one by one. After extraction, the user verifies that there remain no more discs at the bottom of the microplate, and then places the microplate in the washer.
The result is high cost and large space requirement, because of the use of two different apparatus and a substantial prolongation of the duration of the washing phase, the present extractors operating with a single needle (well by well) and the operator having to transfer manually the microplate from one apparatus to the other.
An alternative method consists in returning the microplate manually and to tap it against a flat surface, which constitutes a delicate operation and requires careful verification on the part of the operator.
Finally, for the two alternative methods of extraction set forth above, the risks of plugging the suction needles for liquid of the washing apparatus cannot be entirely overcome, which should give rise to frequent requirements for maintenance and lead to poor washing of the wells that could result in subsequent false analyses.